The case comes two years after senior keeper Richard Hughes suffered fatal head injuries after being crushed against a wall by an elephant.

The prosecution centres around allegedly faulty health and safety systems in the elephant house and the decision to go to court follows an investigation by Chester City Council health and safety officers.

A Chester council spokesman said: "I can confirm that we are going to prosecute Chester Zoo under the Health and Safety Act. We have not yet issued proceedings but we will shortly do so."

The zoo is currently celebrating "Year of the Elephant" in a high profile campaign backed by Coronation actor Chris Bisson.

Mr Hughes, 34, suffered damage in February when he was butted and thrown against a fence by four- tonne female Asian elephant, Kumara. The heavily-bleeding keeper was treated at the scene by paramedics before being taken to the Countess of Chester Hospital, where he lost consciousness.

Mr Hughes, who sustained a fractured skull and shoulder injuries, died 11 days after the attack.

Shortly afterwards the zoo admitted Kumara had previously knocked another keeper over with her trunk.

Health and safety officers at Chester City Council began their investigation into the incident, after issuing a prohibition notice on the animal to ensure she remained behind a barrier at all times.

Campaigns officer Craig Redmond said: "In the past when elephant keepers have been killed we have felt that the investigations have not been as thorough as they could have been.

"We hope that all the facts will be examined along with the reasons why the death of elephant keepers happens on a regular basis."

Mr Hughes had been working in his "dream job" for three years. Ironically, he had been due off on the day of the attack but had offered to cover a friend.

Mr Hughes, who was said to "eat, sleep and breathe elephants" by his father Brian, made the 100-mile round trip to his job at the zoo from his parents' home in Stoke-on-Trent every day.

After the accident his parents, sister and girlfriend mounted a vigil at his hospital bedside hoping for a "miraculous recovery."

They had been given a glimmer of hope when he coughed, a sign that the brain stem was not dead, but his face remained so swollen that it was unrecognisable and he never recovered from the injuries he sustained.

A spokeswoman for Chester Zoo, said the zoo did not wish to comment on the impending prosecution because papers had not yet been served.